This past fall, Mario Hornsby Jr., then a senior at Springfield Central High School, wrote an essay for English class. In neat handwriting on ruled paper, with a couple minor spelling errors, he took stock of his relationship with his father, Mario Hornsby Sr., and his responsibilities toward his mother, Monique, and younger brothers, Drevon and DeAundre.

Just last year I noticed a change in my father’s demeanor. He started to get moody and lathargic. So my first thoughts as a man was to drop out of school and get a job to ease the load of my parents. My father, knowing the power of education, told me to continue school and get a job part-time after school. . . . I always listened to my father’s advice, and it paid off. Now I’m a promising student with a great job, that’s going to suit up for the Central Golden Eagles basketball team this year. My father influenced my life in a great way; he made me a great man who can handle a bunch of tasks. It’s funny, because I was going to be another stastic on the drop-out list, but now the sky’s my limit.

“When I read that letter, it just took me out,” recalls Hornsby Sr. now. “You really don’t know what’s happening in your kid’s life until you get something like that.”

This past fall, Hornsby Jr. started to turn his life around. For most of high school, he was a poor student whose report cards were litanies of D’s and F’s. But senior year, he somehow orchestrated a minor academic miracle. That first semester, his GPA skyrocketed. He made the honor roll. And, having never before played more than a couple of JV basketball games, his newfound confidence and leadership qualities led to his being named captain of the boys’ varsity team.

Then, thanks to the intercession of a helpful coach, something was on the horizon for the hugely popular 19 year old that only a few months earlier would’ve seemed unthinkable: college.

Right about now, Hornsby Jr. should be practicing his jumper, and gearing up for a preparatory year at Brandeis. But he never got to trade the chipped paint and cracked cement of Springfield’s violent Mason Square for the tree-shaded lawns of Waltham. He didn’t live to see his high-school graduation.

On the night of May 17, Hornsby Jr. was hanging out on a friend’s porch, just 30 feet from his own home. From the darkness, shots were fired. The bullets were meant for someone else. Hornsby Jr. ran. He was hit once in the back. He died a short time later.

Now, Hornsby Sr. is making a promise to his son: “I cannot allow this to be in vain.” In the 105 days since Mario’s death, Hornsby Sr. has spent nearly every waking hour — every hour when he’s not working overtime shifts, piloting Peter Pan buses from Springfield to Boston and back — working to set up the nonprofit Do It For Mario Foundation.

INSIDE THE TEDXDIRIGO CONFERENCE | September 14, 2011 I arrived at TEDxDirigo on September 10 feeling rather less than confident about the state of world. The tenth anniversary of 9/11 — and the awful decade that unspooled from that sky-blue morning — was on my mind.